Processing of ultra-fine dispersion of TiB2 in SiC ceramic matrix

SiC/TiB2 particulates reinforced composites have been prepared by in situ reaction : 5, 10 and 15 vol.% TiB2 have been in situ formed through the reaction between TiO2, B4C and SiC. Pressureless sintering process at temperature about 2190 degrees C has been used to densify composites. The influence of composition, of sintering and soaking temperature on the microstructure and the density are investigated. The density decreases with increasing TiB2 content. But dense composites (98% of theoretical density for 5 vol.%, 97% for 10 vol.%, and 96% for 15 vol.%) can be obtained. The open porosity is about 0.1% for 5 vol.%, 0.2% for 10 vol.% and 2% for 15 vol.%. Size distribution of TiB2 is investigated by images analysis. It shows that 75% of the particulates for 5 vol.% TiB2, 60% for 10 vol.% and 55% for 15 vol.% had a size below 1 mu m. Mechanical properties (microhardness, toughness) are investigated.